Well with the insane def skills they have, and their insane damage dealing skills, you can probably just get a +9 cranial cross shield(lol at the guy who wanted tamuran in his), and normal pvp/woe reductions.

So what build is best for pvp? Other then a cranial shield, what other gear is good? I was thinking of getting Variants Shoes, and maybe some battleground gear. What other expensive gear is good (other then god items/mvp cards)?

Well, I dunno much on Royal Guards but isn't that putting the cart WAY before the horse? I say wait till renewal before you do any real planning of a third class build.

As for crusaders, non of them have any really awe-inspiring pvp/mvp moves of note, and their strongest DPS technique IIRC is a linked shield boom spam. For build, I honestly can't say ANY of them do a really noteworthy job of getting the MvP on most bosses. The class as a whole is a defensive one, so going for most damage taken to MvP would be a good prospect.
And expensive gear shouldn't be a problem if you haven't even decided on a build yet. Work out the kinks in your basic abilities first and you'll be able to search the database for stuff to use at trans/high levels. The Crusader page on the wiki shows recommendations on the two most common builds, and looking at posted saders in the "Post your Sader/Pally" thread is the easiest way to get some ideas. On pvp gear: Battlegrounds set and Cranial Shield. Swap the boots for anything else you can get if you're on a server with non-demi homunculi and see one coming, triple damage isn't fun for anyone. Really simple stuff if ya look in a few threads will do.

I personally have leveled a crusader to lvl 99 as a Grand Cross build.

They are mostly good in supporting other classes and players, PvP wise (namely Sacrifice that takes damage from party members). Crusaders don't have a great offensive PvP skill until they hit Transcendence basically. Grand Cross in PvP isn't that great as an offensive skill (of course if your going against those squishy assasins, rogues, hunters, or monks without assumptio<nontrans classes>)

For MvPs, I guess we don't or shouldn't solo any of them without some help lol...

we should, at least, have 1 priest or HP to buff you before taking an MvP boss. I personally have done MvPing as a grand cross crusader but because of my build, I can only go for specific bosses that take ridiculous amounts of holy type damage(demon, shadow, undead). I don't know about shield saders and MvPing so the next person below me will tell you about it probably.

well, i don't really know about royal guards... since its still quite a time for my server to have 3rd jobs. but if a pally, i not sure about iro, but in ero here, either players make vit dex pally or vit agi pally...

well, actually it's kinda depends on the thread starter's play style, since u can either have high dex to cast Sac faster ( even better if with Mjolnir for a instant cast ) or have high Agi to kills... ^^ both the pallys have weakpoints tho...

with no dex equips u wouldnt be able to get instant cast... the lowest base dex you can get is about 66 and still get instant cast (requires alotta goodies tho)

For pvp its a matter of opinion... you could either be RS, MR or support with GD/Sac.
If you wanna MVP its either GC or Sac. With sac its easy to do high-tier MvPs with a group, with GC you can easily do lower tier MvPs by yourself.

But I like playing the Paladin class the most because of how adaptive the class is, find ways to work around how you like to play

Overbrand - BIG AoE hit, in WoE without push back always hit 3 times, its a meele hit (its fun some HP or AB try to defend with pheuna :P), you can use it inmediately after moon slasher, so you can hit easy the sit players - lvl spear quicken increase dmg

Shield Press - high dmg, high % of stun (70% at lvl 5), this stun effect its special bc its longer that normal stun, some dmg ignore flee (maybe the shield weight) so even with a miss you have the chance to stun

(ATK + shield weight + Refine)*(60% + 43% * skill lvl * base lvl/100)

This skills will help you lvl up as an agi char, you must understand in almost all skills % dmg cards are useless, all formulas are based on weapon Atk, other equip Atk, cards that add Atk (andre, ZBear), stats, shield weight, shield refine, base lvl of your RG, and the lvl of other skills, but the element of the weapon works

with the imperial spear & imperial shield comming VP & SP will be very powerfull